The compound 3,5,5-trimethyl-4-[(E)-3-oxo-1-butenyl]-2-cyclohexen-1-one, an intermediate useful for preparing cartenoids, has been manufactured by oxidizing .alpha.-ionone with t-butyl chromate [V. Prelog et al., Helv. Chim. Acta 35, 986-992 (1952)]. However, this process yields only 60% conversion within 14 days of reaction time and the yield amounts to only 25% relative to reacted .alpha.-ionone.
A catalytic oxidation process using a cobalt acetate and bromide catalyst is known for compounds containing allylic and benzylic groups [A. S. Hay et al., Can. J. Chem. 43, 1306-1317 (1965)]. Only one example is described for compounds containing allylic groups, namely the oxidation of cyclohexene to 3-acetoxycyclohexene. The product from this oxidation is effected in very low yield.